Raw Skin after Sex

Alright, so my boyfriend and I are sexually active. We use Trojan condoms and we've had KY lube for a while but we only used it scarcely up until now. As of recently my lips down there haven't been staying consistently wet but the inside of my vagina has. We had sex recently (as in tonight) and when we were finished the skin around my vagina was EXTREMELY raw. My boyfriend checked for cuts and he did not see any, but he noted the skin was very irritated. My question(s) is/are: what could be causing the irritation, and is there anything I can put on the raw skin because it stings!!!